How does Query.prototype.j() work in Mongoose ?
The Query.prototype.j() function is used to request acknowledgement that this operation has been persisted to MongoDB’s on-disk journal.
Syntax:
Query.prototype.j()
Parameters: This function has one val parameter of boolean type.
Return Value: This function returns Query Object.
Installing mongoose :
npm install mongoose
After installing the mongoose module, you can check your mongoose version in command prompt using the command.
npm mongoose --version
After that, you can just create a folder and add a file for example, index.js as shown below.
Database: The sample database used here is shown below:
Example 1:
Filename: index.js
javascript
const mongoose = require( 'mongoose' ); // Database connection mongoose.connect( 'mongodb://127.0.0.1:27017/w3wiki' , { useNewUrlParser: true , useCreateIndex: true , useUnifiedTopology: true }); // User model const User = mongoose.model( 'User' , { name: { type: String }, age: { type: Number } }); const query = User.updateOne({name: "Gourav" }, { $set: {name: 'Geek' } }).j( true ); console.log( "Above operation has been persisted to MongoDB's on-disk journal" ) |
The project structure will look like this:
Run index.js file using below command:
node index.js
Output:
Above operation has been persisted to MongoDB's on-disk journal
Example 2:
Filename: index.js
javascript
const express = require( 'express' ); const mongoose = require( 'mongoose' ); const app = express() // Database connection mongoose.connect( 'mongodb://127.0.0.1:27017/w3wiki' , { useNewUrlParser: true , useCreateIndex: true , useUnifiedTopology: true }); // User model const User = mongoose.model( 'User' , { name: { type: String }, age: { type: Number } }); const query = User.updateOne({name: "Gourav" }, { $set: {name: 'Geek' } }).j( false ); console.log( "Above operation has not been persisted to MongoDB's on-disk journal" ) app.listen(3000, function (error ) { if (error) console.log(error) console.log( "Server listening on PORT 3000" ) }); |
The project structure will look like this:
Run index.js file using below command:
node index.js
Output:
Server listening on PORT 3000 Above operation has not been persisted to MongoDB's on-disk journal
Reference:
https://mongoosejs.com/docs/api/query.html#query_Query-j
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